Most peaceful states Most peaceful states The Institute for Economics and Peace recently issued the first ranking of peaceful states in the United States.Rankings were based on factors such as violent crime, incarceration population and the costs associated with violence. Check out the 10 most peaceful states in the nation. Washington Known for its picturesque mountain views, Washington rounds out the 10 most peaceful states at No. 10. A leader on the West Coast, Washington ranked most peaceful in the Pacific division. Iowa Once mistaken for heaven in an Oscar-nominated film, Iowa ranks as peaceful state No. 9. In the 18 years of conducting the study on peaceful states, Iowa has never fallen out of the top 10. Rhode Island The small coastal state of Rhode Island saw a decrease in homicides from 4.28 per 100,000 people in 2000 to 2.94 in 2009. This helped land the state at No. 8 on the most-peaceful list. Massachusetts Massachusetts ranking seventh, showed signi...